Place the double cream into a bowl, preferably a chilled metal bowl. Whisk on medium speed until you get peaks. To avoid whipping too much cream, keep an eye on it. While you prepare the filling, chill the cream in the refrigerator.
Make the cheesecake filling
In a bowl, combine the cookie spread, mascarpone, vanilla extract, icing sugar and salt. Mix the ingredients together using a stand mixer or a hand mixer at low-medium speed. Continue beating until well combined. Use a spatula or a hand mixer to scrape the bowl's bottom and sides. Then, beat the mixer briefly again.
Use a spatula or a whisk to fold the whipped cream in the cheesecake filling. The texture should be still thick and fluffy, but not runny.
Place the filled tin on top of the chilled base. Level it with a spatula. Tap the tin on the counter gently to allow the filling to settle. Put in the refrigerator overnight.